Report on operation "Backfire"

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Copy No. 853

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I

Report on

OPERATION ^'BACKFIRE''

VOLUME V

Recording and Analysis

Prepared for Printing by the Ministry of Supply
THE WAR OFFICE, LONDON, S.W.I

January 1946

I

p

Report on Operation ''BACKFIRE''

MAY TO OCTOBER, 1945

CONTENTS

Volume 5,

SECTION I . Recording and analysis of the trajectory

APPENDIX I. Details of system used to provide impulses for the kine theodolites
APPENDIX 2. Log of operations-
October 1, 1945

October 2, 1945

October 4, 1945

October 15, 1945

APPENDIX 3. Radar drills and search data

APPENDIX 4. Radar modifications

APPENDIX 5. Explanation of " Backfire " survey grid

APPENDIX 6. Trajectory diagrams

SECTION 2. Photographic records

SECTION 3. Fuel characteristics and storage

INDEX

Action photography

Alcohol —

Quantity and data

Railway tank waggons

Angle of sight — ^negative bias in
Application of scale factor — ^grid system
Asbestos clothing — when used
Aspect angle and implications

B.B.C. time signal used

B — Radar — site location : equipment
Behaviour of rockets

Cameras —

Details of for the three launchings

Films used in

Type and numbers used

Capacity of liquid storage tanks
Climb too rapid — ^rate of— No. 3 rocket
Clothing, asbestos — when used

Command post logs

Communications —

Signals

Wireless

Comparison signal strength at R i and R 2
Comparison of theodolite and radar results

Computation of results

Constant following, poor results on GL II

Construction of grid system

Control of kine theodoUtes

Control point, recording

Data—

And quantity — Alcohol

And quantity — Hydrogen peroxide

And quantity — Sodium permanganate

Graphs of SCR 584

Obtained, recording

Quahty of the SCR 584

Rocket I

Signal, R I, R 2 and R 5
Deployment of kine theodolites
Details of cameras for the three launchings

Diagrams, trajectory

Drill and modifications to equipment
During flight, tracking rockets

Echoes, sustained fall of shot

Equipment —

Location ; site — B — radar
Used — cameras ; searchlight

Fall of shot —

Observing— Site R 4

Plotting ...

Sustained echoes

Field operation, priority of

Para

58

69

70

53
17
66

39

13

5

21

59
61
62
45,60
68
26
66
19

14
15
41
52
31
48
16
4
14

69

71
73
55

2

51
22
42

3
61

56

12

I

46

5
59

Films used in cameras

Flight data— Rocket 3

Fuel-
Characteristics and storage
Cut oflF, reason for not clear-
Cut off— Rocket 2

-Rocket 2

Para

62
27

63
25
23

31

48
49
50
55

17
16

71
72

33
24

2
I

44
46
20

General — computation of results

GLII—

Poor results on constant following

Range 110,000 yards doubtful

Useless " putter on " for more accurate radars

Graphs of SCR 584— data

Grid system — '

AppUcation of scale factors

Construction of

Hydrogen peroxide —

Storage and transport

Individual performance of radars

Initial acceleration — Rocket 2

Introduction —

Recording data obtained

Tracking rockets during flight

Kine —

Control ... 4

Theodohtes —

Deployment of 3

Performance of— Rocket i — Oct. 2 28

Liiquid —

Storage and transport tanks for 67

Storage tanks, capacity of 68

Liquid oxygen 63

Oilin 65

Purity of 64

Location, site, equipment — B radar 5

Logs, command post 19

Meaning results of theodolites 32

Modifications to equipment and drill 12

IVegative bias in angle of sight 53

Observing fall of shot — site R 4 10

Oil in liquid oxygen 65

Oxygen — quantity used 63

Performance of kine theodohtes — Rocket i — Oct. 2 28

Photographic records, stiU photography 57

Photography —

Action 58

Still 57

Plotting fall of shot ... 44

Priority of field operation 20

Purity of Hquid oxygen 64

IIVDEX {cent:}

Quality of the SCR 584 data

Quantity and data —

Alcohol

Hydrogen peroidde
Sodium permanganate . .

Radar —

B, site; location; equipment

Individual performance of

General

Range of rocket signal

Re-deployment of

Sites —
R I — observations of rocket flight
R 2 „ ,j J, J,

•^ 3 }j a )i jj

-^ , 5 jj j> 33 33

Radar and theodolite results — comparison . . .

Railway tank waggons — alcohol

Range of rocket signal '.

Rate of climb too rapid — No. 3 rocket
Reason for fuel-cut-ofF not clear — No. 2 rocket

Recording data obtained

Recording control point

Recording time of take-oflf— site R 5

Re-deployment of radar

Results — computation of

Results of—

Rockets launched ,

Theodohtes — ^meaning

Rocket — transfer of sodium permanganate into
Rockets —

Behaviour of

Launched — results of

Rocket No. i —

Behaved normally

Data

Rocket No. 2 —

Initial acceleration

Reason for fuel cut-off not clear

Suffered fuel cut-off"

Oct. 4th functioning of posts

Rocket No. 3 —

Flight data

Rate of chmb too rapid

Oct. 15th — ^functioning of posts

Signal of

R I, R 2 and R 5 — signal data

R 4 — no fall of shot observed

Scale factors, application of— grid system ...

SCR 584 data, quahty of

Searchlight

Para

69

71

74

5

33
39

54

7

34
35
36
37
38
52
70

54
26

25

2

14
II

7
31

18
32

74

21
18

21
22

24

25
23

29

27
26
30

45
42
47

77

5

59

Signal —

DataRi, R2andR5

Of rocket 3

Range of 110,000 yds. from rocket 2 doubtful ,

Strength at extreme ranges

Strength at R i and R 2, comparison of

Signals communications

Site —

Location; equipment — B— Radar

Ri—

Signal strength

View in direction of laimching site

R2—

Signal strength

View in direction of launching site

R 3 ; tracking rockets near vertex

R 4 ; observing fall of shot

R 5 ; recording time of take-off

Radar R i — observation of rocket flight

Radar R2— „ „ „

Radar R 3— „ „ „

Radar R 4— „ „ „ „ ...

Radar R 5— „ „ „ „ ...
Sodium permanganate

Quantity and data

Transfer into rocket

Storage and characteristics of fuel

Storage and transport of hydrogen peroxide

Storage and transport tanks for liquid

Survey

Sustained fall of shot echoes

System, grid — construction of

Take-off, recording time of— -Site R 5
Tanks —

Liquid storage, capacity of

Storage and transport, for Hquid
TheodoHte and radar results, comparison . . .
Theodolites —

Kine, deployment of

" Meaning," results of

Time signal from B ,B.C

Tracking rockets —

During flight

Near vertex — site R 3

Trajectory diagrams

Transfer into rocket — sodium permanganate
Transport and storage of hydrogen peroxide

Variation of signal strength . . .
View in direction of launching site-

Ri

R2

Wireless communication

Para

42
45
49
43
41
14

40
6

40
8

9
10

II
6
8

9
10
II
73
73
74
63
72
67
16
46
16

II

68
67
52

3

32
13

I

9

56

74
72

39

6

8

15

Recording and Analysis of the Trajectory sectioiv J

INTRODUCTION

1 . SCRs 584, GLs II and a Type 14 Radar were deployed
along the western coast of the Danish peninsula to track
the rockets during flight and to determine their point of
fall. In order to obtain more precise data of behaviour
during the period of burning kme theodolites were used
to produce a precise optical record of the initial part of the
trajectory.

2. " X " Special Radar Battery and No. 2 AA (ATS) KT
Detachment were made available to operate radars and
kine theodolites, respectively, and a detachment of nine
HAA recording vans to record the data obtained. By
suitable tie-up between radar and optical results it was
hoped to gain experience of the accuracy and the general
behaviour of radars used in tracking long range rockets.

DEPLOYMENT

A. — Kine Theodolites (KTs)

3. Two German Askania kine theodolites were obtained
to supplement the two brought from the United Kingdom
by the KT Detachment. Four posts were established as
follows : —

^^:566?|jJ}"S"tish"AskaniaKTs(F6oo lenses)
KDRR;59957977}^™^ ^^^ ^Ts (F300 lenses)

4. Kine Control was established beside KT site A in a
HAA recording van. This site was also Radar Site R 5.
A diagram of the deployment is at Plate i. All four posts
were connected to Kine Control by an omnibus speech
circuit. Individual lines radiating from Kine Control to
the four posts supplied the impulses for the cameras.
These lines were for the most part in German underground
telephone cables. By means of mechanical clock and the
appropriate electrical circuits at Kine Control, all four
KTs were pulsed simultaneously twice per second. In
addition, an electrical counter was made to move with the
pulses, and the counter was photographed 12 times/sec.
beside a i/ioo sec. stopwatch (see later description of site
R 5). After preliminary Hne troubles the system proved
satisfactory. For details of the pulsing system see
Appendix i to this Section.

B.— Radar

5. Five sites were deployed with equipment as follows
(see map at Plate 2) : —

All SCRs 584 except that at R 5 and all GLs II were
fitted with long range modifications.

6. It was desirable to avoid sites to the east of the river
ELBE as they were in the German Army concentration
area " G." Site R i was therefore deployed south of the

SITE

LOCATION

EQUIPMENT

Ri

BENDORF RN 090125

(later at TONNING RM.786361)

(Nord de Guerre Zone Grid)

2 SCRs 584

2 HAA Recording Vans.

R2

I of NORDSTRAND VB.8167
(North European Zone Grid)

I SCR 584 (with 8 ft. para-
boloid).

I GL II.

For Rocket 3 a second SCR
564 (with N2 gate and
auto-follow in range) was
deployed

I HAA Recording Van. A
second van was deployed
for rocket 3.

R3

EMMELSBULL VW.763048
(North European Zone Grid).

I SCR 584.
I GL II.

I HAA Recording Van.

R4

RINGKOBING VR. 724502.
(North European Zone Grid).

I AMES Type 14.
I GL II (modified).
I LW (AA No. 4, Mk. Ill)
(Rocket 3 only).

I HAA Recording Van.

R5

DOSE RR.615891

(Nord de Guerre Zone Grid)

I SCR 584 (with cine camera
on paraboloid).

I HAA Recording Van (with
Cine camera).

KINE-THEODOUTE DEPLOYMENT.

Plate

E N

A Post 661491-2 789113-8

B .. 656603-3 783056-2

C - 663466-6 784002-7

D •• 659948-4 779772-3

\

<^.

Bftiat.

Scale. 1:50.000.

3000

wAmm

4000 YARDS.

DPost.

^/

^^/

•%'

CUXHAVEN.

©CFbst.

Kiel Canal. Originally the site was very similar to that
at STEENBERGEN in HOLLAND, which had been used
to observe rockets launched from the HAGUE area at
LONDON. At a late date, however, tlie proposed line of
fire was swung 4° further west, thus making aspect angles
from this site less favourable. The equipments were sited
on the highest ground in the area with a clear field of view
in the direction of the launching point. The two SCRs 584
were deployed side by side. It was found that so sited,
mutual interference due to imlocked pulses (running
rabbits) was such as to make simultaneous operation of the
sets impossible. When looking towards the launching
site the dipoles of the radars were intervisible. Thus, for
the first two launchings only one radar was in action at this
site.

7. The results from R5 on Rockets i and 2 had been
unexpectedly good and actually of longer duration than
from R r. R i was therefore of Httle use in its first
position. As Area " G " had been reduced in size it was
decided to move R i further north to a position where it
could be expected to obtain trajectory data beyond the end
of the plot produced by R 5. Re-deployment was carried
out in time for the third and final launch on Oct. 15. A site
at TONNING (RM7836) recommended by A.O.R.G.,
was chosen in order that the maximum length of follow
would be achieved, although it was reaUsed that the head
on aspects Hkely to be encountered might make following
difficult at first. Recording of the equipment was done on
a Westex Recorder modified to receive selsyn data trans-
mission from two SCRs 584. An accurate i/ioo sec.
stopwatch was used.

8. Site R 2 was also chosen to have a good field of view in
the direction of the launching site. The SCR 584 here
was fitted with an 8-ft. paraboloid with the aid of which it
was hoped that the rocket would be followed from launch.
This did not prove to be so, and it was found that a longer
aerial spinner was necessary where an 8-ft. paraboloid was
used. This had not been supplied with the parab oloid but
was obtained in time for Rocket 3. For Rocket 3 a second
SCR 584 with an N^ gate, borrowed from the R.A.F., was
deployed. This radar was modified for auto follow in
range by means of a unit provided and fitted by IX Air
Defence Command, United States Forces, European
Theatre. A GL II with normal array was deployed with
the intention of obtaining constant following to provide
trajectory data and to assist the SCR 584 to pick up the
target should it fail initially. The aerial heights were
modified slightly to give optimum results, and provision
was niade for putting the SCR 584 on target by suitably
marrying the magslip and selsyn transmissions (see
Appendix 4). Recording was carried out in the normal
manner using a i/io sec. stopwatch.

9. At R3 both SCR 584 and GL II were sited with the
intention of picking up and tracking rockets as they neared
the vertex of the trajectory. As at R 2 the GL II was in-
tended to do constant following and if necessary to put the
SCR 584 on target. For this purpose data transmission
was modified in the same way as at R 2. On account of
the high angle of search siting was not critical. Recording
was carried out in the normal manner using a i/io sec.
stopwatch.

10. Equipment at R4 was deployed with the intention of
determining the fall of shot. The unmodified AMES Type
14 radar was sited on a suitable hummock some 20 ft.
above the surrounding ground with a clear view in the
direction of the target area. The GL II fitted with the
normal BB modification was originally sited on the assump-
tion that rockets would be fired at a range of 320 kms.
(200 miles). The shorter range of 250 kms. (156 miles)
made the expected aspect angle of rockets unfavourable,
but it was nevertheless decided to retain the radar but
with aerials set so as to lower the beam. By this means it
was thought that air break-ups might be detected which
would be missed by the Type 14. The GL II was sited
normally on flat ground. An unmodified LW set (AA
No. 4, Mk. Ill) was deployed to observe the fall of shot of
Rocket 3 in order to test its suitabiHty in this role. It was
sited as for the Type 14. All recording at R 4 was done
manually.

11. At R 5 an SCR 584 was sited on the sea wall roughly
8,000 yards from the firing point. A long follow was not
expected due to aspect angle and range rate considerations,
and the set was therefore not modified for following beyond
32,000 yards. Recording of the selsyn data on a Westex
Recorder was done by means of a Filmo 70 DA Cine
camera, running at 12 frames per second. Time was
provided by a i/ioo second stopwatch. On the dial board
of the recorder was situated an electric pulse counter which
provided the means of tying up kine theodolite and radar
records. The exact time of take-off of rockets was recorded
by means of a light which was switched on automatically
by the rocket as it lifted from the firing table (an external
" Abhebekontakt "). On the paraboloid of the SCR 584
was fitted a Cine Kodak camera with a 6" telephoto lens.
This recorded at 16 frames per second a picture of the
accuracy of follow of the radar.

12. At Appendix 3 will be found details of the " drill "
carried out at each radar site together with the search data.
Appendix 4 contains details of modifications carried out to
SCRs 584 and GLs II. It was necessary to devise a special
long range modification to the former sets on account of
the unsuitability of the Westinghouse modification for
fitting to sets made by the General Electric Company.

13. No special apparatus was installed to tie up in time
data recorded at the various sites. A special BBC broad-
cast of the Greenwich time signal at half-hourly intervals
between 1400 hrs. and 1600 hrs. each day was arranged.
These signals were received by all recording vans. AH
stopwatches were started simultaneously at 1400 hrs. or on
a later time signal if launching was delayed. They were all
stopped simultaneously on the time signal immediately
following the recordings.

SIGNALS COMMUNICATIONS

14. A Recording Control Point was established at
RR615891, at the same place as Kine Control, KT Site A
and Radar site R 5. Thus at RR615891 were one SCR 584,
one kine theodoHte, and two HA A recording vans. One
of these vans housed kine control with its speech and
impulse lines to all KT sites, and the second van the
recording gear for the radar and the speech lines to all
radar sites. Communication to the radar sites was by direct

DETAILS OF AIMING POINT. LINE OF FIRE &
RADAR DEPLOYMENT

Plate!

line to HQ X Radar Battery (HUSUM) and thence by
radiating pairs to sites R i, R 2 and R 3. Ali recording
vans used telerepeaters Mk. I, and by using one at the end
of each line it proved possible to have all radar sites on the
Une at the same time. The recording vans at the recording
control point had a line to the command post at the firing
point. A second line was available as a standby.

15, It was originally intended that R 4 (in DENMARK)
should be served with lines communications in the same
way as R I, R 2 and R 3, but delay ia installation forced
this station to rely on the alternative wireless net. This
was provided by a Wireless Section equipped with No. 33
sets. One of these sets was deployed at each of sites R i,
R 2, R 3 and R 4, with two sets at the Recording Control
Point (R 5). The sets were netted R 5 to R 4, and R 5 to
R I, R 2 and R 3, two nets being necessary to cover all
the sites. The net R 5, R i, R 2, R 3 was able to work
RT. : that to R 4 only W,T. A diagram of the signals
layout is given in Plate 3.

20, It was decided before launching commenced that
where the requirements of the field operation clashed with
those of the flight recording, the field operation would
have priority. Therefore, launchings were not delayed if
radars or kine theodolites were out of action.

BEHAVIOUR OF THE ROCKETS

Rocket i

21. Judging from the fall of shot this rocket behaved
normally. Using a time switch to give fuel cut-oflf a 50
per cent, zone for range of ± 10 kms. should be expected
of " normal " shots, since in the absence of an integrating
accelerometer or radio fuel cut-off no allowance is made
for variation in bmner performance. The closeness of the
fall of shot to the point of aim (1-9 km. short) is satisfactory
evidence that the thrust unit behaved normally. It was
unfortunately not possible to plot the exact position and
time of fuel cut-off from the recorded results due to the
unsteadiness of the velocity graph obtained from the
kine theodoUte records.

SURVEY

16, 20 Special Survey Det, RA, carried out the survey of
the kine theodolite and radar sites. It was decided to
construct a special grid system to co-ordinate the results of
all recording sites. This was necessary because two grids
(Nord de Guerre and North European Zone III) were
involved in the area, and the Nord de Guerre grid was so
far extended from its origin as to be insufficiently accurate
for the purposes of recording. The " BACKFIRE "
Grid was therefore constructed. It consisted of the North
European Zone III extended southwards and swung about
a point near to the launching site in order to have the same
orientation as the Nord de Guerre zone grid. The co-
ordinates of this point on the " BACKFIRE " grid were
taken to the same as those on the Nord de Guerre Zone
Grid,

17, Certain scale factors were appUed in order that
distances measured on the grid between latitude 53° 40' N,
and 55° 00' would not differ from the true distance by
more than 0-62 part in 1000, This margin of error held
good for distances measured to points further north if
measured from the launching point. All survey and com-
putation of results was carried out using this grid system.
Further details of the grid wiU be found in Appendix 5.

RESULTS

18, During the first phase of operations, Oct, 1-6, two
rockets were successfully launched (Oct. 2 and 4). On
Oct. I two unsuccessful attempts were made to launch the
rocket which was eventually launched on Oct, 4 One
further rocket was launched during a special demonstration
on Oct, 15.

22. The velocity graph shows that the rocket had an
initial acceleration of 0-89 g, rising to more than 3 g. in the
region of fuel cut-off. The velocity at fuel cut-off must
have been of the order of 1,410 m/sec. to give the observed
range. The angle of inclination to the horizontal at fuel
cut-off was 39°, and the observed time of flight 287
± 5 sees. The vertex height above groimd was 69-4 kms.
The rocket fell 1-2 km. to the left of the line of fire, corre-
sponding to an error in fine of 0*28°.

Rocket 2

23. This rocket suffered fuel cut-off after 34I sees,, by
which time it had achieved a velocity of 520 m/sec. and
was at an inclination of 58° to the horizontal. The range
to the fall of shot was 25-0 kms., the vertex height 17-4 kms.
and the total time of flight 136 ± i sees. The rocket fell
0'99 km. to the left of the fine of fire, corresponding to an
error inline of 2-3°.

24. The initial acceleration of the rocket was i-02 g.
Thus the thrust of Rocket 2 was 10-15 per cent, greater
than for Rocket i, resulting in a greater acceleration than
normal. This impression was also gained by experienced
Germans who observed the take-off.

25. The reason for early fuel cut-off is not clear. It could
not have been fuel cut-off due to overrunning of the
turbine (schnellschluss) since the centrifugal switch which
gives the cut-off signal for this is not energised until 40
sees, after take-off. It is certain that no physical break-up
of the rocket occurred, neither did it burst into flames,
since this would have been observed by the kine theodoHte
operators. From the theodoHte films it would appear that
flames were still being emitted from the venturi for some
6 sees, after the rocket ceased to accelerate.

19. The Command Post Logs giving the sequence of
events on these days is at Appendix 2. It will be observed
that with the exception of the failures on Oct. i and delay
in fuelling on Oct, 2, all other launches went according to
plan with little or no delay.

Rocket 3

26, No visual results are available for the trajectory above
2,000 ft. The acceleration at take-off was i-02 g,, which is
greater than the normal value. This is confirmed by the
radar results which show that although the trajectory was

K SITE
A

^

SIGNALS LAYOUT FOR RECORDING
FIRING POINT

Plate 3

ROCKET

Q

COMMAND POST

RECORDING CONTROL POI^ T

KINE

CONTROL

Pulse
ClocK

Omnibus

KIne

SplTech

RVIOI

"^

Take-oFF^
Indicator Lamp

t

KS RECORDER

RADAR

CONTROL

KB KC KD
SAHLENBURG

JI

B

RVi09

307 BDE

HSCR
584

R4 RI-2-3

SIGS
WIRE-
HLESS

UNIT

HUSUM
B HQ

X RADAR

(Emergency Line to /\ A A A
X Radar BHq) Ri R2 R3 R4

standard m space the rocket climbed more rapidly up its
trajectory than it should have done. In spite of this, it fell
i8-6 kms. short of the aiming point. This indicates either
that the time switch operated several sees, sooner than it
ought to have done, or that thrust deteriorated after
45 sees., or that fuel cut-off was given by overrunning of the
turbine (schnellschluss).

27. Time of flight was 274 ± 3 sees, and the vertex height
is estimated to have been approx. 64 kms. above ground.
The rocket fell 5-3 kms. to the right of the line of fire,
corresponding to an error of 1-3° in the line of fire.

PERFORMANCE OF KINE THEODOLITES
Rocket i — Oct. 2

28. The weather was good, with an almost clear blue sky.
All posts fimctioned correctly without hitch. " A '* post
lost target before the others due to a patch of cloud. Due
to a fault in the cine camera in the R 5 recording van
which caused the film to blur, thus making the pulse
counter illegible, it was not possible to tie in these results
with the radar results with any great accuracy. The exact
time of take-off in relation to the theodolite records could,
however, be obtained from the records of " B " post.

Rocket 2— Oct. 4

29. The weather was cloudless with slight high haze.
Only two posts (A and B) functioned correctly, " C " post,
due to Hne trouble, was only working locally, and " D "
post was out of action with a faulty camera motor. " A "
post lost target after approximately 50 sees, due to haze.
" B " and " C " posts followed the projectile down to
zero elevation at a distance of 25 kms. from the firing point.

Rocket 3 — Oct. 15

30. Low cloud covered the area. The target was lost in
cloud at 2,000 ft. All theodolites functioned correctly.

GENERAL

31. Computation of results revealed that synchrony of the
four theodolites was not perfect. Results were worked out
using pairs of bases, and it was found that CD base gave
results which tended to lead those of AB. Photography
of a spinning gramophone disc revealed only very slight
errors of synchrony between instruments when they were
working close together without long lines. The newer
instruments acquired from the Germans were a little
quicker to act than the older " British " instruments, but
the greatest difference between instruments did not exceed
1/60 sec. The conclusion is that the source of the trouble
was delays in pulse transmission through the long lines
from the Kine Control Point to the KT sites.

32. Meaning the results of all available theodolites pro-
duced useful results for an appreciable distance beyond the
fuel cut-off point. Velocity curves were rather unsteady
in the region of fuel cut-off. This was because the rocket
and flame became invisible on the film some time before
cut-off, and in evaluating the film it had to be assumed that
the rocket was in the centre of the field of view.

INDIVIDUAL PERFORMANCE OF RADARS

33. In addition to the breakdowns which caused certain
equipments to be out of action during the firing, about

75 per cent, of the equipments had serious breakdowns at
one time or another during the preparatory stages and in
intervals between launches. The majority of troubles was
due to failure of components such as transformers, motors,
condensers and resistors. This is probably symptomatic
of equipments which have been in storage for a fairly long
period. The performance of the various sites is dealt
with in detail below.

RADAR SITE R i

34. Rocket i. — Only one SCR 584 was in action. It fol-
lowed the rocket for 33 sees. The initial signal/noise ratio
was 6 : i, and range of pick-up 65,000 yds. Aspect angle of
target lost was approximately 100°. The second SCR 584
was out of action due to trouble with the long range
modification.

Rocket 2. — One SCR 584 was in action. The signal
appeared as before but was lost after 6 sees, when the radar
locked down on to groimd echoes. A fault was later dis-
covered in the anti-lockdown modification. The second
SCR 584 could not be used due to mutual interference.

Rocket 3 . — New site at TONNING. Increased spacing
between radars allowed both to operate simultaneously with-
out interference. Both SCRs 584 saw the rocket with 5 — i
signal strength and locked on. The signal faded rapidly
after a few seconds. One radar attempted to lock on a
second time when the rocket was some 20 kms. above
ground (range 60,000 yds. and aspect 80°), but the
radar did not track and the signal faded. The rocket
probably went through the edge of the radar beam.

RADAR SITE R 2

35. Rocket i.— The SCR 584 and the GL II failed to
observe the rocket. It was later found that a longer spinner
was necessary to work with the 8-ft. paraboloid and this had
not been supplied. In the case of the GL II a fault was
later discovered in the transmitter band pass filter which
was causing loss of power.

Rocket 2. — Both radars were in action but failed for the
same reason as given for Rocket i.

Rocket 3. — The 2 SCRs 584 (one with an 8-ft. parabo-
loid and N^ gate) saw the target for a few seconds only.
Signal/noise ratio was i| : i at each. The signals faded
immediately and no tracking was done. The rocket was
not seen subsequently. The GL II followed in range only
for 18 sees. The signal/noise ratio was 2 : i, which was
insufficient to allow constant following in bearing and
angle.

RADAR SITE R 3

36. Rocket i.— The SCR 584 did not observe the rocket
probably due to the natural hazards of scanning the sky for
a fast moving target. The GL II observed the target i min.
54 sees, after launch at a range of 79,200 yds., bearing
217-8% A/S 457°. The target was lost after 21 sees. The
radar track shows an apparent horizontal velocity of the
rocket of 1/6 of the true value. The angle of sights was 9°
too low and the bearing rate of change 6 times too small.
The slant range was also approximately 10 per cent, too
small. The initial signal/noise ratio was 3 : i falhng to
4:1.

Rocket 2.— The SCR 584 was out of action and could in
any case not have been observed since the rocket fell short.
The GL II saw the target for i sec, 70 sees, after launch at
a range of approximately 1 10,000 yds., bearing 214°. The
break faded before it could be brought to the cross wire.

Rocket 3.— The GL II was out of action with VT 98
valve filament and transformer defects. The SCR 584
picked up the rocket unaided and tracked for approximately
15 sees, at a range of 83,000 yds.

RADAR SITE R 4

37. Rocket i.— The Type 14 PPI was out of action. The
radar observed a saturation break at 85,000 yds. range
(E 557550J N 1,01 1,500 Backfire Grid). Range and ampli-
tude were steady for 30 sees, which the radar transmitter
tripped. Estimated accuracy was ± 500 yds. in range and
± I J° in bearing (± 2,000 yds.)

GL II — ^no target seen.

Rocket 2.--The rocket fell short, beyond the range of the
radars.

Rocket 3.— The Type 14 radar saw the fall of shot at
78,000 yds., bearing 240° (E 570100 N 998500). The signal
was less strong than for Rocket i : signal/noise ratio was
initially 5 : i becoming 4 : i almost immediately. The
signal diminished to zero amplitude slowly. It was visible
for 68 sees. The LW Radar (AA No. 4, Mk. Ill) saw the
break for approximately i sec, 3 sees, earlier than the
Type 14 at a range 79,200 yds. bearing 246° (± io°)-
GL II — ^no target seen.

RADAR SITE R 5.

38. Rocket i. — Immediate pick-up was obtained, The
signal faded and the radar ceased accurate following at
15,000 yds. The radar operator tended to overrun in range
by expecting a greater rate of increase of velocity than
occurred. Film from paraboloid camera was useless due to
over-exposure.

Rocket 2. — The target was lost at 20,000 yds. due to
fading signal. The camera on the paraboloid gave good
results. Higher ratio gears were fitted to the range unit to
allow higher range rates to be produced. These produced

somewhat erratic operation due to imperfect fitting, but did
not increase the range of tracking.

Rocket 3.— The target was lost at 29,000 yds. The
camera on the paraboloid was useless due to cloud.

RADAR GENERAL

SCR 584— Variation of Signal Strength with Aspect
Angle and its Implications

39. In the absence of special recording apparatus no actual
measurements of signal strength could be made to relate
signal strength to aspect angle. Some very strong im-
pressions as to its effect were however gained. Site i in
its initial position south of the KIEL CANAL was known
to be poorly sited, and a long follow was not expected.
Experience with such a site had already been gained with
an SCR 584 deployed in HOLLAND observing launchings
from the HAGUE and HOOK OF HOLLAND areas.
When re-deployment was considered sites at HEIDE
(RM 8723) and TONNING (RM 7736) were the alterna-
tives. In order to achieve the maximum distance of follow
the latter site was chosen. This site, however, produced
no success for either of the SCR's 584, the signal being good
initially but fading rapidly.

40. The situation at R2 was similar with the addition that
the initial signal observed was a great deal weaker (1} : i)
even where the 8-ft. paraboloid was being used. The con-
clusion must be that for R 2 and the re-deployed R i the
inclination of the rocket to the vertical was already sufl5-
ciently great at pick-up to reduce signal strength below that
necessary to allow the radar to track at such ranges.

41. It is, however, worthy of note that although good
following was not achieved from the site at TONNING the
range and bearing data at pick-up would have been suflBcient
to obtain a rough pinpoint of the launching site had it been
hostile. At R 2 it is doubtful if such iiSbrmation could
have been deduced from the results since the signal was
not visible for sufficiently long to enable a bearing to be
determined. With the aid of a " side by side " presenta-
tion of the signals produced by the bearing spHt, the bearing
of the laimching position could probably have been
deduced.

42. The actual values of aspect angles for the various sites
were as follows : —

(zero aspect is directly head on, 180° direcdy tail on)

ON TARGET

initial

sig/noise

ratio

target lost

1

RANGE

ASPECT

RANGE

aspect

YDS.

n

YDS.

C)

Ri (first site)

65,300

90

6/1

66,500

100

( « «)

65,200

90

6/1

65,200

91

(second site)

62,000

84

5/1

61,600

79

( « « )

60,000

81

5/1

60,000

81

^ ( - »)

61,500

82

5/1

60,000

74

R2 (assumed values —

(For rocket

(For rocket

radar did not track)

height 2,000 ft.)

height 5000 ft.)

77,000

82

4/1

77,000

75

R5

—

—

—

15,200

151

(abnormal trajectory)

20,100
29,800

120
147

43. It would appear from these results that at a range of
60j000 yds. head on aspect angles of less than 80° cannot
be tolerated if the radar is to track. Even at ranges of
15,000-20,000 yds. the sensitivity of signal strength to aspect
is very marked, although the presence of the flame may
also have aflected the strength of signals received in this
case. On the second rocket the radar followed for some
time after the end of burning. This target was still lost
at 20,000 yds. with an aspect of 120°.

FALL OF SHOT PLOTTING

44. The success achieved by the Type 14 was satisfactory
proof that it can be used to plot fall of shot out to a range of
at least 85,000 yds. and probably considerably more. On
the first rocket a saturation signal was received from a
range of 85,000 yds. It was visible for 30 sees, without
diminution when the radar transmitter tripped and no
further observations could be made. The third rocket
was observed at 78,000 yds. but with a smaller signal
(sig./noise 5 : i). In each case the range to the target
remained unchanged during the whole period for which
the break was visible and the signal was steady. It would
therefore appear that it was a fall of shot phenomenon and
not the descending projectile which was seen by the radar.

45. The signal from Rocket 3 was visible for 68 sees.
During this time the amplitude decreased to zero. Had
the signal been due to tiie column of water one would
expect it to grow slowly and diminish slowly. In fact the
radar echo grew immediately to full strength, dropped
almost immediately by about 1/5, and subsequentiy de-
cayed slowly. A water spout 3,000 ft. high would collapse
in about 14 sees. Had the signal been due to a column of
water, the colunm must have been much greater than this.

46. It is notable that the Germans report observing the
same phenomenon of sustained fall of shot echoes during
their trial work done from Peenemunde. Here they
observed fall of shot by radar (Freya) and reported un-
expectedly good results. They reported large signals
visible long after the physical waterspout had collapsed,
but could offer no explanation.

47. The GL II at R 4 did not observe either of the falls
of shot. The aspect angle of the falling projectile was un-
favourable and observation of the rocket was not expected.
The LW radar (AA No. 4, Mk. Ill) which observed Rocket
3 reported a break some 3 sees, before the Type 14, but the
break did not remain visible for more than i sec. It seems
probable that the echo was the rocket descending through
the radar beam. The time discrepancy was probably
caused by the dead time entailed in traversing the Type 14.

GL II

48. On only one occasion was any constant following
attempted and the results were so poor as to be useless as
track data. The groimd speed of the projectile as given
by the radar was 1/6 of its true value and the height 12 kms.
low. There is also strong evidence that the slant range
of 79,000 yds. was 10 per cent, too small. In spite of the
slant range to the rocket being less than 79,000 in one case
(R 2, Rocket 3) the signal strength was poorer and tracking
was not possible. The cause of poorer signal strength
would almost certainly be the head on aspects of as low as
75° which occurred, although a polarisation effect due to
horizontal aerials may have reduced the signal strength.
The rocket in this case was climbing whereas for R 3 it
was more nearly horizontal.

49. The signal from Rocket 2 observed by the GL II at
R3 at a range of 110,000 yds. must be regarded with
suspicion. It is said to have occurred 70 sees, after
launch. At this time the rocket must have been at the
top of its trajectory (ht. 17 km.) with zero incHnation.
Aspect angle would therefore be approximately 30° (head-
on). This signal was only visible for a few seconds and
disappeared before its range could be measured accurately.
There can, therefore, be no certainty that it was in fact
due to the rocket.

50 . In the only case where the GL II is said to have tracked
the rocket the bearing and angle data were not good enough
to have put an SCR 584 on target. The inability of the
GL II to produce sufl&dentiy accurate bearing and angle
data makes it for all practical purposes useless as a " putter
on " for more accurate radars.

QUALITY OF THE SCR 584 DATA

51 . Apart from the radar data from R 5, two other radars
produced track data. The SCR 584 at Site i followed the
first rocket from soon after launch up to a height of about
30,000 ft. The track produced can be seen on tiie trajectory
diagram at Appendix 6. The second radar was that at
R 3 which followed Rocket 3 at a range of 83,000 yds. just
before it reached the vertex. Here again following was not
good, but the range was extreme. The ground plan and
vertical plots can be seen at Appendix 6, No smoothing
has been done and, in fact, the track is of such poor quahty
as to make satisfactory smoothing impossible.

52. At R 5 it was possible to collect precise data as to the
performance of the SCR 584 by comparison of theodoHte
and radar results. The average errors of following in
bearing, angle and range are given in the table below :

ROCKET

AV. ERROR

BIAS

MEAN DEVIATION

(bias removed)

A/S

CONSISTENCY

NO. OF
READINGS

Bg

A/S

Bg

A/S

Bg

A/S

I

2

0-22°
0-22°

0-27°
0-23°

—•09°
—20°

—23°
—16°

o-i6°
o-i6°

•15°
•16°

•17°
■10°

74
74

13

53. A negative bias in A/S of about 0-04° is to be expected
due to a small displacement for which no correction has
been made. Readings were made twice per second. Con-
sistency is the average of the first differences of adjacent
errors, and is a measure of the smoothness of the radar data.
Further data will be available from the 16 mm. film taken
from the camera on the paraboloid. The film cannot,
however, be evaluated on the Continent and will in any
event not produce results any more accurate than those in
the table on page 13. Evaluation of the film will be
carried out at A.O.R.G.

54. It was expected that the SCR 584 at R 5 would lose
target due to the large range rate. In fact the signal was
so poor at ranges greater than 20,000 yds. that it could not
be held. This is shown by the results achieved on
Rocket 2 where the rocket was followed for some time after
it had ceased to accelerate. It was, nevertheless, lost at a
range of 20,000 yds. Auto-range tracking would therefore
not have increased the range of following, although it would
undoubtedly have improved the quality of the data. It
is interesting that the radar succeeded in holding Rocket 3
out to a greater range than the previous two. This was

the only rocket to go to the right of the hne of fire and as
such would present a sUghdy more favourable aspect angle.

55. Graphs of the SCR 584 data can be seen at Appendix 6.
These show visual and radar data against time. The
aspect angle of the target is also shown.

TRAJECTORY DIAGRAMS

56. At Appendix 6 will be found the following diagrams of
the initial part of the trajectory of each rocket :
(i) Ground plan track

(2) Vertical plane plot

(3) Velocity

(4) Inclination

In the case of Rockets i and 2, kine theodolite data is
available. SCR 584 data from R 5 is given in each case
and SCR 584 data from R i in the case of Rocket i. In
each case the corresponding data for a " normal " rocket
has been plotted. For Rocket 3 the SCR 584 track from
R 3 is given in ground plane and the vertical plane. The
extrapolated trajectory has been plotted on the graphs as
accurately as is possible.

Details of System used to provide
impulses for the Kine Theodolites

APPEIVDIX

The clock, a Contactor Master Type i, closed relay (A)
twice per second. This relay closed a circuit containing
24 volts from accumulators supplying the four kine
theodoHtes in parallel with 25 m. amps.

In parallel with the lines to the kine theodolites was a
second relay (B.) This relay opened a circuit containing
an electrical counter which moved in consequence. At
the end of each impulse the contact at (A) was opened and
at (B) closed, thus arming the coimter in preparation for the
next pulse.

CLOCK LINES K.SITE

r^fifi^?5£:t= ohms. A

eOOohms.z: B

475 ohms. =z C
520ohms D

PULSE
COUNTER

14

I

Log of Ops.— October 1, 1945

APPENDIX

2

f

TIME

SEQUENCE OF EVENTS

TIME

SEQUENCE OF EVENTS

0930

Control point manned

1527

Fuel column left launching site

1043

Fuel column left KRUPPS

1527

Commander, 307 Inf. Bde. reported

1045

Setting up of rocket completed

" All clear "

1050

All kine sites manned

I54I

Meilerwagen departed

1 108

All kine lines tested

1542

Orienting completed

1209

All K.T's colHmated

1542

X-15 warning to recording sites

1330

R I, R 2 and R 3 manned

1546

Insertion of igniter

1400

Watches synchronised with B.B.C,

1549

Steering tests completed

time

I55I

X-3 warning to recording sites

14II

Rocket tests completed

1552.5

Red Verey hght fired

I412

Fuel column arrived at launching

1554

Attempt to launch rocket

site

I75I

X-15 warning to recording sites

1425

Tanking begun

1752

All radars and kines ready for action

1425

X-60 warning to recording sites

1800

Watches checked with B.B.C.

1433

All radars ready for action

181O

X-3 warning to recording sites

1500

Time check

1812

Red Verey light fired

1522

Fuelling completed

1815

Attempt to launch rocket

1523

X-30 warning to recording sites

I815

Stand down

Log of Ops.— October 2, 1945

TIME

SEQUENCE OF EVENTS

TIME

SEQUENCE OF EVENTS

0930

Control point manned

1400

All recording vans synchronised

0950

Setting up of rocket completed

time with B.B.C.

IOI6

Fuel column leaves KRUPPS

1406

Superfluous personnel leave launching

1050

Fuel column arrived special vehicle

site

park

1408

X-30 warning to recording sites

1055

All kine sites manned

1408

Tanking completed. Departure of

1055

Main rocket tests completed

fuel column

II20

All Kine lines tested

1410

All transport clear of temporary car

1200

Fuel column arrives launching site

park

1245

Tanking procedure commences

1415

Igniter inserted

1247

X-60 warning to recording sites

1425

X-15 warning to recording sites

1249

All K.T. colhmation completed

1428

Orienting completed

1305

Radar R 2 reported out of action

1430

Departure of Meilerwagen

Radar N at R i, and Radar at R 5

1432

Type 14 at R 4 ready for action with

reported ready for action

modified range tube

1337

Kine at site C out of action — ^impulse

1436

All kine theodolites ready for action

line not working

1437

Test radar report

1344

Comd. 307 Inf. Bde. reported " All

1437

Steering tests completed. Launching

clear "

troop take cover

1355

Type 14 at R 4 reported out of action

1437

K-3 warning to recording sites

1400

Watches synchronised

1441.12.3 sees.

Rocket launched

15

Log of Ops.— October 4, 1945

TIME

SEQUENCE OF EVENTS

TIME

SEQUENCE OF EVENTS

0915
1006

lOIO
1045

1049
II30
1225

1254
1254
1255

1302

1302
I34I

Setting up rocket completed
Control point named (delay due to

transport breakdown)
Fuel column leaves KRUPPS
Fuel column arrives at special vehicle

park
All kine sites manned
Main rocket tests completed
Fuel column arrives at launching

position
Tanking commences
X-60 warning to recording sites
PreUminary radar report
Only R 5 completely ready for action
All kine lines tested. (Delay due to

fault on impulse line at site B)
K.T. collimation completed
X-30 warning to recording sites

1345

1347

1355
1356
1400
1400
1401
1404

1404
1406
1409

14010
1412
1414
1415.55.09 sees.

Comd. 307 Inf. Bde. reported " All

Clear "
Tanking completed. Fuel column

departed
Superfluous personnel warned oif site
All radars ready for action
Orienting completed
Time synchronised with B.B.C.
X-15 warning to recording sites
All transport clear of temporary car

park
Igniter inserted
Departure of Meilerwagen
Steering tests completed. Launching

troop take cover
Kine site C out of action
X-3 warning to recording sites
Red Verey Hght fired
Rocket launched

Log of Ops.— October 15, 1945

TIME

SEQUENCE OF EVENTS

TIME

SEQUENCE OF EVENTS

0900

0920
1030
1043
1047
II20
II30

II50

1302
1330
I33I

Setting up of rocket completed.
(Preliminary work had been done
ahead of schedule)

Control point manned

All kine sites manned

Fuel column left KRUPPS

Main rocket tests completed

All kine Hues tested

Fuel column arrives at special vehicle
park

Radar report : R i, R 2, R 4 and R 5 —
Ready for action. R3 — SCR 584
ready for action. GL II — High
angle cams being fitted. Estimated
to be ready for action at 1230 hrs

Fuel column arrived at launching site

Tanking procedure begins

X-60 warning to recording sites

1400
1430
1430

1432

1432
1450
1452
1454

1455
1455
1458
1500

1502

1504

1506.26.5

Recording vans synchronised time

Time check with B.B.C.

Comd. 307 Inf. Bde. reported " All

Clear "
Tanking completed. Fuel column

departed
X-30 warning to recording sites
All transport clear of car park
Warning to clear launching site
All radars on the air and ready for

action
Orienting completed
Igniter inserted
Meilerwagen departed
Steering tests completed. Launching

troop takes cover
X-3 warning to sites
Red Verey light fired
Rocket laxmched

To accommodate the distinguished visitors the normal time
allowed for the procedure was extended by 45 minutes. This
explains the gaps in time between various events. Though

not necessarily following the normal sequence in time, the
procedure for preparation was carried out without a hitch,
although the tanking procedure did take longer than usual.

X6

Radar Drills and Search Data

APPEl^DIX

3

GL II STATIONS at R 2 AND R 3

1 . Equipments were mamied and operated as for normal
aircraft engagements, and laid on the calculated crossing-
point bearing. (The aspect at crossing-point is 90°).
Ranges were set on the potentiometer scale corresponding
to approximately 2,000 yds. in excess of the expected
crossing-point range, to allow for pick-up shordy before
crossing-point.

R 2 Search Range 70,000 yds. Angle 30°.

R3 „ „ 84,000 „ Angle 45°.

2. The transmitter aerial switch was permanently left at
" Follow " and " Follow " drill was ordered by GL I on
receipt of the signal given from the command post at the
firing point 3 minutes before launch. " Sig. Sel " was
not used and bearing and angle operators used a con-
tinuous bright trace. This was useful in cutting out the
effect of sUght errors in time-base tracking.

GL II STATION at R 4 (Range only)
3. This equipment was operated as for a normal BB
watch, with Operators i and 2, and recorder-timekeeper.
(BB = Big Ben, and refers to the procedure used during
Operation " CROSSBOW.")

SCR 584 at R 3

6. This equipment was directed at the crossing-point
bearing angle and range with an angle search of ± 100 mils
carried out by an extra operator. On the report " Target,"
No. 3 set in a clockwise rate of change of bearing of
approximately i°/sec. This was necessary to hold the
target in the beam for a sufficient length of time for
strobing and switching to " Automatic."

Search data : —

R3

3,965 nuls

Angle
800-1,000 m^s

Range
82,000 yds.

SCR 584 at R 5

7. The equipment was directed at the fixed bearing and
range of the firing point, and at a fixed angle of 5°,
"Target" was reported by No. 2 when the signal was
visible in strobe patch, and No. 3 switched to " Auto-
matic." In the later stages of following it is necessary for
No. 2 to follow using the " slew " hand wheel.

Search data : —

Bearing Angle Range

R5 - 224° 5° 7,800 yds.

GL RANGE CALIBRATION

4. Cahbration pips were checked against Westex readings
daily, and immediately after engagements.

SCR 584 EQUIPMENTS at R i, R lA AND R 2
5. A small search area approximately 3° each side of the
surveyed bearing of the firing point was covered and a
range approximately 1,000 yds. in excess of the surveyed
range was set. It was thought necessary to carry out a
small search to cover possible ahgnment errors and at the
same time to " paint " the PPI. Angle setting 20 mils
was employed. Normal operating driU was carried out.
In the case of R 2 " 2nd lay " was ordered by No. i if no
pick-up was made within 30 seconds of " Shot," and range,
bearing and angle figures corresponding to crossing-point
were then set, with a search in angle of ± 100 mils.

Search data : —

Bearing
Ri ... 4,292 mils
RiA ... 3,610 „
R2 ... 3,428 „

Angle
20 mils
20 „
20 „

Range
65,210 yds.
61,900 „

79,775 »

AM.E.S. TYPE 14 at R 4

8. This equipment was operated normally and traversed
over an arc of ± 15° each side of the bearing to the target
point, increased to + 15° and — 30° for Rocket 3. The
average time of the complete double traverse for the 30°
search arc was 8 sees., and for the 45° search arc 10 sees.
The PPI was not employed and all readings were taken by
obtaining a maximum break on the range tube by bracket-
ing for bearing and subsequently reading the range and
bearing scales.

Search date : —

Bearing
R 4 ... 240° — ^270°

Rocket 3 ... 225° — ^270°

L W at R 4

Angle Range

0° 70,000 — 100,000 yds.
0° 70,000 — 100,000 „

9. This equipment was operated for Rocket 3 only. The
serial array was in "low" position and drill normal.
Search data as for Type 14, Rocket 3.

17

Plate 4

Radar Modifications

APPEIVDIX

A.— MODIFICATIONS TO SCR 584 TO ENABLE
THE EQUIPMENT TO TRACK OVER A RANGE
ZONE OF 32,000 YDS. BETWEEN o AND 96,000 YDS.

1. General. — The standard extended range modification
to the equipment was taken as a basis. Further components
had to be added or existing components changed in value
to ensure stability of operation of the range unit. Stable
tracking was then possible in range over any desired range
zone of 32,000 yds. between o and 96,000 yds. The
standard modification includes an extensive modification to
the gearing in the range indicator imit. This was not
necessary using the method described below.

2. — ^Method. — The 1.7 kc. multivibrator, 1.7 kc. ampli-
fier, narrow gate and wide gate circuits were modified as
shown in attached circuit diagram (PLATE 4). The existing
20K narrow gate potentiometer in the range indicator imit
was removed and replaced by a 20K Hohal potentiometer.
This was set so that a resistance value of 14K existed across
piQS A and C of the potentiometer when the range indicator
was set at zero. The 20K potentiometer labelled " Speed "
was mounted on the chassis for screwdriver control.

3. The 5 K.N.G. delay potentiometer was mounted on the
chassis for screwdriver control and was replaced in its old
location by a 25 K potentiometer to give the operator a less
fierce control over the narrow gate delay.

4. Setting Up. — The range unit was set up as far as the
5 kc. multi-vibrator by the CRO method. The " 17 kc."
was then adjusted to count down four times. The " Speed,"
N.H. delay and N.G. potentiometers were then adjusted to
ensure range tracking in the range zone between 32,000
and 64,000 yds. It is then possible by movement of the
narrow gate delay to bring the " narrow gate " (visible as
a bright patch on the course range tube) to any range
between o and 96,000 yds. and smooth strobe tracking
over the selected range is possible.

5. Where a range zone selected does not lie between
o — 32,000, 32,000 — 64,000 or 64,000 — 96,000 yds, it is
advisable to mark the course range indicator with a line
to which the N.G. Strobe is aligned when the operator is
adjusting N.G. delay.

B. MODIFICATION TO GL II EQUIPMENT FOR
LONG RANGE CONTINUOUS FOLLOWING

GL RECEIVER

6. Aerial System.— (a) At Site R2 the elevation aerials
were fixed at normal height for the frequency in use and
the bearing and range aerials were all adjusted to o-sA.

(b) At Site R3 the bearing and range aerials were
dropped to 0-4 A to increase the angle of the lobe, and in
addition a high angle cam was fitted and the heights of the
elevation aerials altered accordingly.

7. Time Base Modifications. — (a) To increase the length
of time base scan two -ooi UF 5000V porcelain condensers
were connected in parallel with the main time base con-
denser on both the range time base unit and the bearing and
elevation time base unit. This was done by drilling two
J-in. holes in the panels and screwing down the condensers
on each panel. The tops of the condensers on the range
time base panel were connected to terminal 23, whilst those
on the bearing and elevation time base panel were connected
to terminal 27. "^

(b) The resistors R32D to L on the range time base
panel were removed and substituted by eight 220 K ohms
3 watt resisters.

8. Kipp Modifications.— (a) The Kipp was modified to
give a longer negative pulse by connecting a -002 UF 350V
working condenser across C42A and a o-i UF 350V working
condenser across C40A.

(b) A o-i UF 350V working condenser across C26A was
fitted to increase brightness of " putter on " stroke (B.S.E.).

9. Calibrator Modifications. — To enable more pipe to
be received on the C.R.T.S. the caUbrator circuits were
modified by

(a) Connecting a -oi UF 350V working condenser
across C12C and C26B.

(b) Inserting a 100 K ohm, 1/2 watt resister between
terminal 3 and terminal 40.

10. IF Modifications. — (a) The video frequency ampli-
fiers were removed and output stage and power pack con-
verted to normal working. IF's were peaked to give i Mc
bandwidth. Sensitivity as measured by 3/1 signal noise
ratio method was less than 5 /aV.

GL TRANSMITTER

11. Modulator. — The two output Pen 46 valves were
replaced by ET 44 valves.

12. Oscillator. — Two -ooi UF 5000V condensers were
connected across the grid condenser of the oscillator to
give a wider transmitted pulse.

19

C. MODIFICATION TO PERMIT SCR 584 FOLLOW-
ING OF GL II COARSE BEARING DATA
13. In order that the SCR 584 could foUow the GL
equipment in azimuth the remote selsyn on the position
indicator xmit was coupled to the coarse Bg magsHp trans-
mitter in the GL receiver. Existing leads to the magslip
were disconnected and terminals i, 2 and 3 connected to
terminals 9, 10 and 11 of the terminal strip in the position
indicator unit. These terminals are of course directly con-
nected to Si, S2 and S3 of the remote selsyn. The rotor
of the selsyn was energised from its usual 115V source of

supply. A pair of leads was connected to terminals 14
and 15 (i.e.j 11 5V supply to sels3nti) on the position indicator
unit and connected to the X and Y terminals on the magshp
through a 200 ohm resistance. This produced 67V at
terminals X and Y. A switch was incorporated in this
circuit so that the power to the magslip could be switched
off when not required to avoid overheating.

14. Tests were carried out and it was found that the
remote selsyn followed the Bg magsUp within ±1/2 degree
when variations of 5 degrees were made.

Explanation of " BACKFIRE ''
Survey Grid

APPEIVDIX

OUTLINE OF PROBLEM

1. The requirements were (a) orientation and fixation in
strict geodetic relationship of a number of points in the
launching area, (b) orientation and fixation of radar stations
along the Danish Peninsula, (c) the setting of a grid that
would agree as nearly as possible with the map grid (Nord
de Guerre) in the launching area and on which both (a)
and (b) could be combined with reasonably true relationship.

SURVEY IN THE LAUNCHING AREA

2. A normal triangulation which included several trig,
points was carried out and a mean azimuth and scale
corrected distance for a baseline were obtained. Nord de
Guerre co-ordinates using true distance values were com-
puted for Station WOOD and co-ordinates were then
computed for the remaining points.

SURVEY OF RADAR STATIONS

3. Nord de Guerre or European Zone III co-ordinates
were obtained from 1/25,000 maps or trig, data and
orientation from metro and/or trig. data. These values
were then converted to the " BACKFIRE " grid by the
methods outlined below.

THE " BACKFIRE " GRID

4. Owing to excessive scale factors involved the Nord de
Guerre projection was not suitable for the area to be
covered, and the North Exuropean Zone III projection was
used. To agree with the condition laid down in para, i (c)
the values obtained on this projection were then given a
simple change of grid based on the Nord de Guerre and
European Zone III values obtained for Station WOOD.

CONVERSION FORMULAS

5. Station WOOD.

" BACKFIRE " Co-ordinates : 656,147-0 783,450-0
Nord de Guerre do. : Same as " BACKFIRE "

European Zone III do. : 1,151,632-58 199,045-38

EUROPEAN ZONE III TO " BACKFIRE "

6. Let :

a = Bearing change in grids = 10° 16' 20" (to
nearest second).
Ee

_ Diflf. E and N from WOOD in European Zone
~ III values.
Nej

Eb 1 _ Diff. E and N from WOOD in " BACKFIRE"
Nb 1 values.

k ■= a scale factor = 0-999415
Sina= 0-178324053
Cosa= 0-983971803

m = k sin a = 0-17821973
n = k cos a = 0-98339618
Then:
Eb = Ee.n - Ne.m
Nb = Ne.n + Ee.m

NORD DE GUERRE TO "BACKFIRE"

RIGOROUS METHOD

7. Using Lambert Projection Tables :

(i) Convert Nord de Guerre to French Geographicals.

(2) Convert these to Danish Geographicals.

(3) Convert Danish Geographicals to European Zone

III.

(4) Convert to " BACKFIRE " by metiiod outiined

above.

SCALE FACTORS METHOD

8. Let A = a point for which both Nord de Guerre and
" BACKFIRE " co-ordinates are known.

B = a point for which the " BACKFIRE " co-
ordinates are required.

k = " BACKFIRE " scale factor = 0-999415.

ki = Scale factors from German Nord de Guerre
charts for the Alid Point of the base AB.*

kg = Scale factor from North European Zone III.
Tables for the mid latitude of the base AB.

C = Angle of conversion between " BACKFIRE "
and Nord de Guerre grid for the mid point
of the AB (see para. 9).

Then, distance AB on Nord de Guerre values X k. kj.
k2 = distance AB in "BACKFIRE" values, and the
bearing A to B in Nord de Guerre values plus or minus
C = Bearing A to B in " BACKFIRE " value. The
" BACKFIRE " co-ordinates of B can then be computed.

*ki must not be taken from Nord de Guerre Projection
Tables. This method will be reasonably accurate pro-
vided that the point to be changed is not at too great a
distance from P. When large distances, or areas where
scale factors become inaccurate, are involved, the rigorous
method should be used and the scale factors method only
used as a rough computing check.

THE BEARING

9. The angle of conversion of North European Zone III
and " BACKFIRE " grid is constant. For conversion of
North European Zone III bearings to "BACKFIRE"
bearings subtract 10° 16' 20". The angle of conversion
in seconds between " BACKFIRE " and Nord de Guerre
grid for a given point A is found by the following formulse :

Diff. Longitude between point A and Station WOOD
in seconds X 0-08299.

East of WOOD the Nord de Guerre bearings are the
greater, west of WOOD the lesser.

DISTANCES

10. A scale factor K = 0.999415 has been introduced in
the conversion from European Zone III to " BACKFIRE "
in order that any distance measured on "BACKFIRE"
grid between Latitudes 53" 40' N and 55°oo' N will not
differ from the true distance by more than 0-62 metre in
1,000. This margin of error also holds good for distances
measured to points further north if measured from the
launching area.

GEOGRAPHICAL COORDINATES

1 1 . Nord de Guerre grid is based on French values.

European Zone III and Danish grids are based on

Danish values.
1/25,000 maps of the G.S.G.S.4414 Germany series
give German values.
The corrections are :
French to German Lat. + 1-30" Long — 3 '15"
German to Danish Lat. — 6-40" Long + 1-20"
The Geographical values for Station WOOD are :
German values : Latitude 53°5o' 30-19"

: Longitudes o8°35' 15 -oi" East
of Greenwich.

TABLES USED

12. The Lambert Projection Table for the Nord de
Guerre and North European Zone III issued by the Office
of the Chief Engineer, Washington, D.C., 1943, and the
German scale factors chart issued in the SHAEF Survey
Tech. liistr. No. 138, dated 10 March, 1945, were used.

LIST OF MAP REFERENCES ON THE " BACKFIRE"
GRID

13. Kine
A
B
C
D

Theodolite Posts

Eastings
661491-2
656603-3
663466-6
659948-4

Northings
789113-8
783056-2
784002-7

779772-3

Ht.

7-12
12-21

0-98
26-38

14. Radar Equipments
R I SCR 584 North

SCR 584 South
E I (Redeployed)

SCR 584 East

SCR 584 West
R 2 SCR 584

GLII
R 3 SCR 584

GLII
R 4 Type 14

GLII
R 5 SCR 584

708825-0
708825-0

678701-0
678523-0
672652-0
672698-0
661296-0
661374-0
631844-0
631760-8
661512-0

812575-0 36
812550-0 36

836174-0
836016-0

855175-0
855131-0
891803-0
891878-0
1,034152-9
1,034204-8
789116-0

6

6

05

05

01

7-1

15. Launching Site and Aiming Point
Surveyed Point

(Collimator) 656470-3

Launching Point 656459-6

Aiming Point 557930-0 -,^-_,

Bg of line of fire (uncorrected for rotation of earth)

336°46' 35" (" BACKFIRE " = Nord de Guerre)

or 337° 25' 25" true.

784040-3 13-67

784043-9 13-67

1,013680-0 0-00

Trajectory Diagrams

APPENDIX

6

ATTACHED ARE THE FOLLOWING TRAJECTORY DATA DIAGRAMS :

L GROUND PLAN TRACK . . . . .

2. EXPANDED GROUND TRACK PLAN OF TAKE-OFF

3. VERTICAL TRAJECTORY DIAGRAM . .

4. ROCKET VELOCITY— TIME GRAPH . . . .

5. ROCKET INCLINATION— TIME GRAPH

r = 1 km.

1 cm. = 2-5 metres

1" = 1 km.

" = 100 m/sec.

" = 4 sees.

" = 10 sees.

" = 4 sees.

) ROCKET 1

6, 7, 8, 9, 10— AS ABOVE FOR ROCKET 2.
11, 12, 13, 14, 15— AS ABOVE FOR ROCKET 3.

16. ROCKET 3— GROUND PLAN TRACK OF SCR 584 DATA' FROM R 3.

17. ROCKET 3— VERTICAL TRAJECTORY DIAGRAM OF SCR 584 DATA FROM R 3.

18. ROCKET 1— GRAPH OF RANGE, BEARING, AND ANGLE OF SIGHT AGAINST TIMES
FROM SCR 584 AT R 5 AND KINE THEODOLITE SITE " A."

8000

7000

&000-

795000

^OOO

3000

2 000

lOOO

790COO

9000

8000

7000

bOOO-

7850OO-

iCOO-

5000-

ROCKET No.L GROUND PLAN
2nd. OCT. 1945. 1441 hrs.

DIAGRAM

RADAR (R.i)
RADAR (R.5)

in

O

2000[- 5

X

cc
O
ioooh^

78axx)

LAUNCHiNGSlTE

EASTINGS

_J L_

-J 1 I !_

-J L

feSOOOD 1000 2000 3000 4000 W5O0O foOOO 70CX) 8000 9000 iMXCC-

784075

70

65

60 -

55

50

45

40 -

35

30

784025

- «/)

o

z

_ 5

a
o

L Z

-1 « ^ 1 1 1 > f

DIAGRAM 2

ROCKET N?l,

2nd. OCT. 1945.

GROUND PLAN.

Scale: I cm. rep. 2*5 m. -

TIME IN SECONDS
FROM SHOT,

WIND SPEED 5 m.p.h.
WIND BG. 360^

EASTINGS.

_L L-.^ J -J 1 L

J I I L

656445

50

55

60

65

70 656475

-

DIAGRAMS

ROCKET No. 1. TRAJECTORY.

55"^

^ ./-^SS-J"

2nd. OCT. 1945. 14-41 hrs.

y'^5^-B'

50V/ . ■'
/ , >9-8"

■

'

/^' /^ ' RADAR(R.I)

/f-''

'

■y'^^

yAsr

//'^54-8"
//

/ ^'

/ ^

A- 30 -3"
//'^50-l"

-

5« /.f25-8"

^ /f25-r

Ui /'■

. rao-r

-

# (5 ■ 1 "

|»0-8"

no*r

GROUND RANGE IN Kms

1 1 1 1 1 1 — 1 1 1 ,,. J 1 -J

-J 1 1

fO li

12 IS i4- IS

DIAGRAM 4

.

«»

>-

h-

8

15^

-J

"~"

LU

.

>

m

•

^

■""

0^

O

»™i™

1^.

H

I—

o

O

"O

o

c

0£

Q<

DIAGRAM 5

IS

^

o

b

n.

<

^

2:

^

ji

<

E

im:

e»

O'

;^

•|j

H

»u

^

X'

(C^

OS

p-5

*»! IIOSi.¥Hn08«l

7000

6000

795000

4000 -

3CKX)

2000

KXX)

790000

9000

8000 -

7000

6000 -

785000(- I

X

40O0 - ^

7B3000

-J- r

1 r

DIAGRAM 6

ROCKET N9 2. GROUND PLAN.
4th OCT. 1945. 14.16 krs.

35 ^FUEL CUT-OFF.

LAUNCHING SITE.

EASTINGS

J I I L

_l L

650000 lOOO 2000 3000 4000 5000 6000 7000 8000 9000 660000

DIAGRAM 7

095

085

075

065

055

045

784035

ROCKET N^2. 4.10.1945.
GROUND PLAN.
Scale: I cm. rep. 2*5 m.

WIND BG
170°
WIND SPEED Sm.p.h

TIME IN SECONDS
FROM SHOT.

EASTINGS.

612

656435

445

455

465

"T— r

-! — — — — r-

DIAGKAM 8

14 .

15 .

12 .

10

ROCKET No.2. TRAJ ECTORY
4th. OCT. 1945. 14.16 hrs.

GROUND RANGE IN Km':

DIAGRAM 9

>

^

1-

X

u

NO

o

1

5!

fS

in

o-

'^

T

ON

— ^

H

H*

lU

(>

^

u

O

X

Qi

^

QNOD3S aSd S3aiaN Nl A1I0O13A

T 1 1

DIAGRAM 10

z

a

e\j

►O

S

-J

«£>

OJ

,

o:

m

Z

'"t

f-

22

UJ

»-:

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o

■L:

cr

"^

diO-xna n3nj -

o
I

s J ,

•S33«03a Nl WOIIVNIIDN!
_J 1 L.

8000 .

DIAGRAM II

\

ROCKET

N?3. GROUND PLAN.

IS^J^OCT

. 1945. I5.06 hrs.

\ \
\ /

A

A\

-

-

\ \
\\
\ x

\ \
\ \

.

-

\ \
\ \
\ \

-

-

^

\45"
\ \
\\ '

-

\ Y^q"

-

-

V35"
V

V 30"

"

V25"

Vzo"

- CO

O

Z

X

O
z

EASTINGS

1 1 1

-1 1 . . 1

650000 1000 2000 3000 4000 655000 6000 7000

9000 660000

950

9^5

9(H)

879

8SrO

8^5

80-0

77^

75-0

72-5

TO'O

675

650

62-5

60*0

57-5

55-0

5^5

500

DIAGRAM 12

ROCKET N?3 >
15^ OCT. [945.

Scale: I cm. rep. 2-5 m.

^0« TIME IN SECONDS

FROM SHOT.

X
47-51- 2

45-0.

784042-5

WIND SPEED 25 m.p.h.
WIND 86.320^

EASTINGS

J I L

656440 42-5 45-0 47-5 50-0 52;5 55-0 57-5 60-0 62-5

DIAGRAM .13

I 575"

ROCKET N?5. TRAJECTORY
I5*^0CT 1945 - 1506 hrs.

MO" GROUND RANGE IN KILOMETRES.

J L

10

J L

DIAGRAM 14

t

i

o

X

q

<o

J

o

UJ

>

!£!

to

iO

o

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1

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I I \ L

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—

^

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tn

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U

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DIAGRAM 15

00

o

o

S33bOaa Nl NOIIVNIIDNI

882

878 -

874-

870 -

866 -

8b2 -

858 -

85^

, , J , „,

DIAGRAM 16

-

r

\

\

Ai-f^

.

\

/ ROCKET N0.3. 15.10.45.

.0^

SCR 584 at R3. GROUND PLAN

J00\

Scale : Icm. rep. 1 Km.

\

V^

-

\ r

/V^b-4

\\

"^JS

-

' \ \

O

z

^59-9

X

a
O

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Y592

EASTINGS

1

i 1

616

bio

b24

628

632

T 1 T"

— 1 1

1

— J —

"T r r-' I

o

DIAGRAM 17

•

«

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-

\*

.

L

o

"

\ 1

=

•

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DIAGRAM 18

;■-/—•/

280 - 56

278 1- 54 _ "/■^///ll

ROCKET N°l. 14.16 HRS. 2"^QCT. 1945. /^~ //!

2761-52 ~ ../ I' I

RANGE. BEARING. ANGLE OF SIGHT AND HEIGHT FROM // / /

^74 [-50 SCR 584 AT R5 COMPARED miW KI DATA . /" // '^

272 h 48 / / /

RADAR

/.^

270f-46 KT. -_ // / / 9-j

/ // //

268 U4 / // ,/

2B6-42 // // / 8

/ // /

264^40 / / /

2621-38 / / / 7

if / / /

258 1- 34 / // !/ // 6

/ / // /

2601-36

2541-30 / ,/ / /Is

// / / / 2

,252|-2B°cN / ,/ / / o

? 250 -26- // ,/ il I '-4

- - / ,/ / / !

1 248 - 24 txi // // / /

§246^22 < //■ / / S3

2441-20 # / /

>--^ / /

242 h8 .// / / 2-1

, / • / ./

240 M6 ,/"■ / / /

X

/"

.^^ / / /

238 M4 ,-^-'^ / / y I

236 M2 ,^^ / / ./"

/ / y/'

234 MO ^/ ..>-

232-8 _ RANGE _ £_ ..^......--'-■"-^'""" /''

230 \ 6 x^^/'' ./

■^26 I" 2 BEARiNG ^^--^^^^ TIME. ! IN. = 2 SECONDS

o7f"-"?o'"'"9^ 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58

16

15

o

o

13 2

12^

z
3

91° 96° 107° 119° 130° 139°

ASPECT ANGLE ASPECT ANGLE ASPECT ANGLE ASPECT ANGLE ASPECT ANGLE ASPECT ANGLE

Photographic Records .

SECTIOIV

2

STILL PHOTOGRAPHY

57. Photographs of the installations, equipments, proce-
dures, and launchings were taken by the British Army Film
Photographic Unit (A.F.P.U.) using a Zeiss Super Ikonta,
6 cm. X 6 cm., 2-8 Zeiss Tessar lens camera and by the
U.S. Army Signal Corps Photographic Unit using a Kodak
Speed Graphic 5-in x 4-in camera.

ACTION PHOTOGRAPHY

58. A detachment of the British Army Kinematograph
Service was employed to take shots which will be used in
the preparation of a training film. The object of the film
is not to record operation " BACKFIRE " but to show
how the A-4 works, its handling from railhead to firing
point, and the process of laimching. Shooting commenced
on Sept. 12, 1945, and was completed on Oct. 22, 1945.
All sequences were shot at KRUPPS or the firing site, with
the exception of a few shots of German operational
launching positions in The HAGUE area.

59. The equipment used was :

(a) Cameras

3 Newman cameras
I Mitchell camera
3 Vinten cameras
I Eyemo camera

(b) Searchlight equipment

3 X 5 kw lamps
6 X 2 kw lamps
3 X 500 kw lamps

with remote control
gear for filming
launchings.

60. For filming the launchings on Oct 2, Oct 4, and
Oct 15, 1945, remotely controlled and manually operated
cameras were used. The remote controlled cameras were
positioned on two gun shields which were erected on the
launching site (see Plate 5). The cameras were started
from the command post.

OCTOBER 2, 1945. First Launch.

(a) Remotely controlled cameras,
(i) Gunshield i.

I Vinten 40 mm. lens 32 f.p.s. fixed frame
Ascent of rocket.
(ii) Gunshield 2.

I Vinten 6 in. lens 32 f.p.s. fiaced frame.

Base of rocket.

I Eyemo 2 in. lens 32 f.p.s. fixed frame.

All rocket.

(b) Manually operated cameras.
Operated from hghthouse 2,000 yds. S.W. of firing point.

I Mitchell 2 in. lens
I Newman 12 in. lens
I Newman 6 in, lens

192 f.p.s. fixed frame.

Ascent of rocket.

24 fp.s. Following

ascent of rocket.

52 f.p.s. Following

ascent of rocket.

OCTOBER 4, 1945. Second launch.
(a) Remotely controlled cameras,
(i) Gunshield i.

I Vinten 40 mm. lens

(ii) Gimshield 2.
I Vinten

2 in. lens

I Vinten 6 in. lens

32 f.p.s. fixed frame.
Ascent of rocket.

96 f.p.s. fixed frame.

AH rocket.

32 f.p.s. fixed frame.

Base of rocket.
(b) Manually operated cameras.

Situated 640 yds. in rear of Shelters i and 2.
I Mitchell 12 in. lens 192 f.p.s. \ All cameras
I Newman 12 in. lens 24 f.p.s. I covered ascent
I Newman 6 in. lens 32 f.p.s. | from take-oflf to
I Eyemo 3 in. lens 32 f.p.s. j smoke trail

OCTOBER 15, 1945. Third Launch.

(a) Remotely controlled cameras.

As for second launch on October 4, 1945.

(b) Manually operated cameras.

Positioned in slit trenches S. of command post 60 yds.
from the rocket.

(Covered ascent
of rocket from
take-oflf to dis-
appearance
cloud.

61. Details of cameras used for the three launchings are
as follows :

62. On all launching days the cameras used infra red film
except the 2 A.K.S. Vintens. Other sequences were shot
with Kodak Plus X or Super XX.

41

DETAILS OF LAYOUT LAUNCHING SITE.

\

Plate 5.

Scale: 1:2500

COMMAND POST.

'LEGEND

• DISTRIBUTION CHAMBER.
n PHOTOGRAPHIC SHIELD.

Fuel Characteristics and Storage

SECTION

3

I

LIQUID OXYGEN

63. Quantity required per rocket = 5,000 kg. (10,930 lb.)
Purity = 98 per cent.
Boiling temperature under

atmospheric pressure = — 183° centigrade

Latent heat = 52 cal. per gram.

(water = 560 cal. per
gram)

64. When standing in the tanker, liquid oxygen has the
interesting property that its purity actually improves, the
gas which boils off carrying a large proportion of nitrogen.
There is no need to include a purity test at the site as the
factory material is above 99 per cent, oxygen.

65. Any particles of oil in the liquid oxygen, present by
mischance, tend to float to the top when it is standing in
the tanker. It is then a good practice to avoid completely
emptying the tanker.

66. For the men engaged in transferring the oxygen from
the rail tanker to the road tanker, and subsequendy to the
rocket, the Germans provided complete sets of asbestos
clothing.

67. Storage and transport tanks are double- walled with
the inner tank of copper or aluminium and the outer wall
of steel plate. The inter-space is filled with insulating
material of a non-combustible character in powder form.

68. When the external size is restricted as in rail or road
transport sacrifice has to be made in the extent of the
insulation provided. This is brought out in the following
table for tanks which were used in the operation.

TANK

CAPACITY

THICKNESS OF INSULATION

FASSBURG
STORAGE

56 tons

40 inches

RAIL

30 tons

12 inches

ROAD

6| tons

9 inches

ALCOHOL

69. The standard material used was ethyl alcohol, as this
gives an increase in range of about 30 kms. (260-290 kms.)
over methyl alcohol.

Quantity required per rocket = 4 tons (8,150 lb. or

3700 kg. approx.), but
varying according to
range.
= 75 per cent.
= -8599 at 15° centigrade,
and '8556 at 20° centi-
grade.

Concentration by weight
Specific gravity

Freezing temperature
(100 per cent, material)

= — 130° centigrade

70. The alcohol railway tank waggons used by the Germans
are of a series of different types of up to 20 tons capacity.
They have bottom connections for emptying through the
portable alcohol pump.

HYDROGEN PEROXIDE

71. Quantity required per rocket = 126 Htres (370 lb.).
Concentration by weight = 78-80 per cent.
Specific gravity (A-4 Fuel) = 1-34

Specific gravity (100 per cent,
material) = 1-4633 at 0° centi-

grade.
Freezing temperature (100 per

cent, material) = -1-9° centigrade

(but undercook
easily)

72. Hydrogen peroxide is stored in aluminium tanks
whose capacity varies from 300 tons, as at Duneburg, to
20 tons, as at Kiel. Two types of rail tankers have been
encountered, viz. — a large single tank of 20 tons capacity,
and a smaller size with four separate cross-tanks each of
2^ ton capacity, making 10 tons in all. The small tanker
was the one usually used for transporting hydrogen
peroxide for the A-4 rockets to the railhead. Top con-
nections alone are provided. The transfer of liquid to the
road tanker is made by a pump whose suction hose is
inserted through the top opening. Hoses used are made of
Mipolam.

SODIUM PERMANGANATE

73. Quantity required per rocket = 11 htres (31 lb.)

Specific gravity
Purity

= 1-26

= 27 per cent, solution

74. This comes forward in sealed cans, each with a
capacity of about two gallons. It is transferred into the
rocket direcdy from one of these cans by the use of a tin
funnel.

43

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